The Siq or al-Siq (Arabic: ??????) (translated: the shaft) is the main entrance to the ancient city of Petra in southern Jordan. The dim; narrow gorge (in some points no more than 3 meters wide) winds its way approximately one mile and ends at Petra's most elaborate ruin; Al Khazneh (The Treasury).

Petra was first established as a city by the Nabataean Arabs in the 4th century BCE; and owed its birth and prosperity to the fact that it was the only place with clear and abundant water between the Hijaz trading centres of Mecca and Medina; and Palestine.

Hewn directly into the Nubian sandstone ridges of the south Jordanian desert; it seems probable that - given its excellent defensive position and good water supplies - Petra has been continually occupied from as early as Paleolithic times. It is thought to be mentioned in the Bible as Sela; a mountain fortress captured by Amaziah; King of Judah; in the 9th century BC; when the defenders were hurled to their deaths from the summit; and as many as 10;000 people died.

The city's Latin name; Petra - literally; 'Rock' - probably replaced the biblical name Sela at the time of the Roman conquest some 1;900 years ago. Today; in Arabic; the ancient site is still called Batraa; though the valley in which it is situated is known as Wadi Musa - 'The Valley of Moses' - being one of the places where; according to semitic tradition; the Prophet Moses struck a rock and water gushed forth. Truly Petra is steeped in history.